JEPG (Joint Photographic Experts Group) 2000 is known as a coding method of encoding coefficients of respective sub-bands (frequency bands) generated by performing band division processing with respect to an inputted image when coding the image (data).
When an image is encoded by the JPEG 2000 method, wavelet coefficients obtained by performing wavelet transform to the inputted image are quantized, and entropy coding is further performed to the quantized coefficients obtained by quantization.
In the entropy coding in related art, bit modeling called EBCOT (Embedded Block Coding with Optimized Truncation) and arithmetic coding called MQ coder are performed. That is, the bit modeling of quantized coefficients is performed and arithmetic coding is further performed with respect to each bit plane based on plural coding passes. Then, codes obtained by the arithmetic coding are outputted as the encoded image (data) (for example, refer to JP-A-2004-166254 (Patent Document 1).
When the image encoded by the JPEG 2000 method is decoded, processing is performed in the order inverse to procedures performed at the time of coding. More specifically, entropy decoding is performed to the codes as encoded image data and inverse quantization is performed, and wavelet inverse transform is further performed to the quantized coefficients obtained by the inverse quantization. Then, the image obtained by the wavelet inverse transform is outputted as the decoded image.